Maternal anemia and long-term respiratory morbidity of the offspring—Results of a population-based cohort

Purpose: To evaluate the association between prenatal maternal anemia (hemoglobin, Hb < 11 g/dl) and long-term respiratory morbidity of the offspring. Methods: A retrospective population-based cohort analysis was performed at a single tertiary medical center. We include all singletons born between 1991–2014 and discharged alive. Offspring with congenital malformations were excluded. The 3 study groups were defined on maternal Hb levels on discharge: severe anemia (< 7.0 g/dl), mild to moderate anemia (7.0–11.0 g/dl) and unexposed (≥ 11.0 g/dl). Offspring respiratory morbidity was predefined on ICD-9 codes and recruited from the hospitalized medical records. A Kaplan–Meier survival curve was formed to compare the cumulative hospitalization and a multivariable Cox survival analysis was used to control for cofounders (gestational age, maternal age, diabetes, hypertensive disorders, post-partum hemorrhage and transfusion of blood products). Results: 214,305 deliveries met the inclusion criteria: 807 (0.3%) mothers had severe anemia, 105,196 (49.1%) mothers had mild-moderate anemia, and the remaining were not anemic (108,302, 50.5%). Respiratory hospitalization was significantly higher among the offspring born to anemic mothers (6.2%; 5.3% and 5.1%; p = 0.020, in the study groups). However, association between maternal anemia and respiratory-related hospitalization remained significant only among the mild-moderate anemic group (adjusted Cox hazard ratio = 1.1; 95% CI 1.05–1.14; p < 0.01). The Kaplan–Meier survival analysis showed significant higher total respiratory hospitalizations in offspring according to maternal anemia status (Log Rank p-value = <.001). Conclusion: Maternal anemia was associated with long-term respiratory morbidity of the offspring.